Investigation of experimental allergic orchitis (EAO) has recently become an important research endeavor since similar testicular diseases occur spontaneously and follow vasectomy. Research progress of EAO has been slow chiefly because of the lack of purified testcular antigens that induce EAO (aspermatogenic antigens), and of pathogenetic studies based on purified antigens. The main objective of this proposal is therefore to determine the relationship between purified or well-characterized sperm cellular antigens and pathogenesis of EAO. Soluble aspermatogenic antigens will be isolated from soluble acromosomal contents (SAC) released from guinea pig (GP) sperm in the presence of inophore and calcium. Aspermatogenic antigens from SAC will be purified using a variety of techniques including affinity chromatography, gel filtration, ion-exchange chromatography, preparative polyacrylamide gel electrophoresis and iso-electric focusing techniques. The number of aspermatogenic antigens in SAC will then be determined. We will next isolate residual bodies and spermatids from dissociated GP testicular cells by unigravity gradient and isopicric centrifugation. Since residual bodies have surface autoantigens while spermatids have both surface and acrosomal antigens, comparison of these two cell types in EAO induction will determine the aspermatogenic capacity of surface autoantigens. Finally, by active immunization of GP with well-defined aspermatogenic antigens and sperm cell fractions, and by passive transfer of EAO with antisera to these antigens, we will be able to correlate the immunopathology and pathogenesis of EAO with sperm and testicular autoantigens with respect to their biochemical characteristics as well as cell-location.